It can infect mammals that eat raw fish in North America.

[2] The testes vary from almost round to oval, and may be deeply lobed or slightly indented.

[2] The receptaculum seminis is elongated or pyriform, and slightly twisted, and situated to the right and behind the ovary.

[8] The definitive hosts are fish-eating mammals such as domestic dogs (Canis lupus familiaris), domestic cats (Felis catus), wolves (Canis lupus),[5] red foxes (Vulpes vulpes),[9] gray foxes (Urocyon cinereoargenteus),[3] coyotes (Canis latrans), raccoons (Procyon lotor),[5] muskrats (Ondatra zibethicus), American minks (Neovison vision),[5] fishers (Martes pennanti),[4][10] or bears.

[8] Sashimi from raw Catostomus commersoni was identified as a source for an outbreak in Montreal in 1993.

[8] After ingestion of fish infected with M. conjunctus, about 1–15 days are needed for symptoms to occur, namely for eggs to be detected in the stool (incubation period).

[12] The acute phase consists of upper abdominal pain and low-grade fever.

[8] Drugs used to treat infestation include praziquantel:[7] 75 mg/kg in three doses per day (the same dosage applies for adults and for children).

[6] M. conjunctus was found to be a common infection of domestic dogs in First Nations settlements in 1973.